Edge insulation for vacuum insulation panels

ABSTRACT

The invention provides an edge insulation piece ( 1 ) comprising a thin sheet of material ( 2 ) which is manipulated by bending, rolling or other forming to effect a long conductive path within a small cross-sectional area. In a preferred embodiment, a thin layer of insulation material ( 3 ) is interleaved between two layers of the thin sheet of material ( 2 ), which is folded around the insulation layer ( 3 ) during forming of the edge piece ( 1 ). A further layer of insulation material ( 4 ) may be rolled within the edge piece ( 1 ) as it is. This interleaving of thin layers of insulation material ( 3, 4 ) prevents the surfaces of the thin sheet of material ( 2 ) from touching each other and also insulates the material ( 2 ) from the top and bottom panels ( 5, 6 ) of a vacuum insulation panel ( 7 ) when the edge piece ( 1 ) is inserted around the edge of the panel ( 7 ). The edge piece ( 1 ) may be further coated over part or all of its length with a low emissivity material ( 13 ) to minimise radiative losses. Alternatively or additionally the coating ( 13 ) may comprise a gas impermeable layer to form a gas impermeable barrier.

[0001] The invention relates to edge insulation, principally but notexclusively for vacuum insulation panels.

[0002] In recent years the need for thermal super insulation materialshaving a thermal conductivity of less than 5 mW/mK has increasedsubstantially. Vacuum insulation panels comprising two walls with anevacuated chamber between them have many advantages as insulationmaterials. In particular, vacuum super insulation (VSI) panels providegood insulation for many applications. With good quality VSI panels, theonly losses normally encountered are radiative and conductive losses.For large panels having a large surface area, edge considerations formonly a small part of the overall loss and tend to be ignored. However,where smaller areas are concerned i.e. 2 m² and less, edge losses canrepresent a significant part of the overall losses. Most Vacuum SuperInsulation panels incorporate radiation inhibitors within the insulationmaterial substrate and rely on fine powder and fibres to minimiseconductive paths. For high temperature applications metal edges have tobe used and the insulation materials are difficult to encapsulate withinthe edge formation and this increases the losses from the edge.Similarly, in order to be effective the edge material has to be as thinas possible and not create conductive paths between the exterior platesof the panel, as well as being as long as possible without makingcontact with itself. U.S. Pat. No. 4,745,015 and 4,444,821 disclose theuse of plastic edges coated in thin metal to provide an adequate sealand others use plastic foil to achieve the same effect. Most plasticsolutions have to limit temperatures to below 120° C., to avoid problemswith shrinkage etc.

[0003] It is an object of the present invention to provide an edgeinsulation that will reduce the losses from encapsulated insulatingmaterials, such as vacuum insulating panels, and any other device,component or part that requires a thermal break. The invention can beapplied to effect an improvement at any temperature difference but it isparticularly effective at elevated temperatures.

[0004] It is a further object of the present invention to provide anedge insulation with improved corner portions.

[0005] The invention provides an edge insulation piece for an insulationarticle characterised in that the edge insulation piece comprises a thinsheet of material, the thin sheet of material having been manipulated toeffect a long conductive path within a small cross-sectional area.

[0006] Preferably the thin sheet of material may be any suitable width,from a narrow strip to a width suitable for making a long edge piecesuch as could form a one-piece edge insulation around an insulationpanel, for example.

[0007] This invention improves the thermal performance of most VacuumSuper Insulation (VSI) panels and reduces the thermal losses normallyencountered at the edges and circumferences of insulating materials. Itachieves this improvement by increasing the conductive length of thematerial between the hot and cold surfaces. A variation alsoincorporates thin layers of insulation sandwiched between each fold orbend in the material. This is achieved without increasing the width byany significant amount and also reduces any convective losses due to thelower average temperature of the edge. The temperature drops along thelength of the sheet forming the edge piece between a hot surface and acold surface to which the edge piece may be attached. The inventionfurther enables the edge of such insulating materials to be able towithstand thermal expansion and additionally creates a structurallystrong edge.

[0008] Preferred materials include for example stainless steel for hightemperature applications, aluminium foil, mild steel, glass or plasticsmaterials which can withstand the required temperatures and pressuresand are sufficiently gas impermeable for the required applications,either by treatment of the material or by coating it with agas-impermeable layer. Potentially any material that is capable of beingproduced in a thin section is capable of being utilised. Ideally thelower the thermal conductivity the better, but even conductive materialscan be used if they are thin enough and long enough.

[0009] Preferably the thin sheet of material is manipulated by bending,shaping or otherwise deforming the thin sheet of material.

[0010] Alternatively manipulation of the thin sheet of material mayinclude forming the edge insulation piece by extruding, moulding orcasting to produce the thin sheet of material in the desiredconfiguration.

[0011] Preferably the thin sheet of material is manipulated to form anedge insulation piece having a substantially square or circularcross-section with the cross-section of the sheet of material being inthe form of a spiral. Alternatively the cross-section of the edgeinsulation piece may be in the form of a wave or zigzag shape.

[0012] Preferably part or all of the surfaces of the thin sheet ofmaterial are coated with a low emissivity material.

[0013] Preferably the thin sheet of material is formed by rolling,stretching or any suitable method and this is coated with agas-impermeable layer and/or a low emissivity layer or other desiredlayer by way of extrusion, electrodeposition and so on.

[0014] Preferably a thin layer of insulation material is sandwichedbetween layers of the thin sheet of material to improve the insulationbetween each layer and to prevent contact of any part of the thin sheetof material with adjacent layers.

[0015] Preferably the insulation is formed by a thin coating deposited,coated or otherwise joined to the thin sheet of material prior tomanipulation of the thin sheet of material.

[0016] Alternatively the insulation may be formed by coating the thinsheet of material after manipulation, for example by immersion in aliquid insulation material, electro-deposition, powder coating,electro-static coating and so on.

[0017] Preferably the insulation is variable in thickness depending uponits relationship to the hot and cold surfaces of the insulation article.

[0018] Preferably the edge insulation piece is formed by folding orrolling the thin sheet of material. Advantageously the thin sheet isfolded to form two adjacent layers, connected at the fold end.Preferably the folded sheet is folded or rolled to form the edgeinsulation piece. Preferably a layer of insulation material issandwiched between the two layers of the folded sheet. Advantageously afurther layer of insulation material is positioned adjacent to one ofthe layers of the folded sheet and is folded or rolled within the layersof the folded or rolled edge insulation piece.

[0019] Preferably the shaped edge insulation piece is squashed to limitits overall size.

[0020] Preferably the edge insulation piece has means to join it toseparated parts of an article, such as the top and bottom parts, thatrequires having its parts insulated from each other, such as a panel.Advantageously the means to join the edge insulation piece to an articlecomprise extending end portions that can be attached to the respectiveseparated parts of such an article by welding, adhesive means or othersuitable means.

[0021] Preferably the extended end portions can be manipulated andshaped to achieve an effective seal.

[0022] Preferably the extended end portions are covered with an inverted‘V’ or ‘top hat’ shaped sealing means to facilitate sealing by means ofwelding, gluing or alternative methods of sealing.

[0023] Preferably the thin material is manipulated by way of a series ofrollers positioned in relation to each other to effect gradual changeswithout significant deformation of the material. Alternatively guidesmay be used to achieve a gradual change in form and shape. Alternativelythe material may be manipulated by a combination of guides and rollers.

[0024] A further problem of using any type of edge assembly is thesealing of the corners. The invention further provides an edgeinsulation piece comprising a corner portion, the edge insulation piececomprising a thin sheet of material with extending portionscorresponding to the corner portion and the thin sheet of material beingmanipulated to effect a long conductive path within a smallcross-sectional area. Preferably the extending portions are triangularin shape. The manipulation of the corner portion can be accommodatedusing the same techniques of bending and folding as for the edgeinsulation piece. Preferably the manipulated corner portion comprises aradiused rolled corner. Most corner shapes can be accommodated usingthese folding techniques. It is feasible that these folding techniquesmay have applications in other technologies.

[0025] The invention further provides a method of manufacturing an edgeinsulation piece having a corner portion for an insulation articlecomprising the steps of:

[0026] providing a thin sheet of material with extending portionscorresponding to the corner portion;

[0027] folding the thin sheet of material to form two layers; and

[0028] manipulating the thin sheet of material to effect a longconductive path within a small cross-sectional area.

[0029] Preferably the step of manipulating the thin sheet of materialcomprises bending, shaping or otherwise deforming the thin sheet ofmaterial.

[0030] Alternatively the step of manipulating the thin sheet of materialcomprises forming the edge insulation piece by extruding, moulding orcasting to produce the thin sheet of material in the desiredconfiguration.

[0031] Preferably the step of manipulating the thin sheet of materialcomprises manipulating it to form an edge insulation piece having asubstantially square or circular cross-section with the cross-section ofthe sheet of material being in the form of a spiral. Alternatively thecross-section of the edge insulation piece may be in the form of a waveor zigzag shape.

[0032] Preferably the method includes the further step of coating partor all of the surfaces of the thin sheet of material with a lowemissivity material. The invention may alternatively or additionallyprovide the step of coating part or all of the surfaces of the thinsheet of material with a thin layer of gas impermeable material toprovide an impermeable gas barrier should this be required.

[0033] Preferably the method includes the further step of sandwiching athin layer of insulation material between layers of the thin sheet ofmaterial to improve the insulation between each layer and to preventcontact of any part of the thin sheet of material with adjacent layers.The invention may alternatively or additionally provide the step ofsandwiching a thin layer of gas impermeable material between layers ofthe thin sheet of material to provide an impermeable gas barrier shouldthis be required.

[0034] Preferably the insulation is formed by depositing, coating orotherwise joining a thin coating to the thin sheet of material prior tomanipulation of the thin sheet of material.

[0035] Alternatively the insulation may be formed by coating the thinsheet of material after manipulation, for example by immersion in aliquid insulation material, electro-deposition, powder coating,electro-static coating and so on.

[0036] Preferably the edge insulation piece is formed by folding orrolling the thin sheet of material. Advantageously the thin sheet isfolded to form two adjacent layers, connected at the fold end.Preferably the folded sheet is then folded or rolled to form the edgeinsulation piece. Preferably a layer of insulation material issandwiched between the two layers of the folded sheet. Advantageously afurther layer of insulation material is positioned adjacent to one ofthe layers of the folded sheet and is folded or rolled within the layersof the folded or rolled edge insulation piece.

[0037] Preferably the method includes the further step of squashing theshaped edge insulation piece to limit its overall size.

[0038] Preferably the manipulation of the thin sheet of material iscarried out by a series of rollers positioned in relation to each otherto effect gradual changes without significant deformation of thematerial. Alternatively guides may be used to achieve a gradual changein form and shape. Alternatively the material may be manipulated by acombination of guides and rollers. In a further alternative the materialmay be manipulated by twisting it.

[0039] The invention will now be described by way of example only withreference to the accompanying drawings, of which:

[0040]FIG. 1a shows a schematic cross-section of an edge insulationpiece according to the invention arranged within a vacuum insulationpanel;

[0041]FIG. 1b shows a schematic enlargement of the circled area of FIG.1a;

[0042]FIGS. 1c,d,e,f and g show alternative embodiments of the area ofthe edge insulation piece shown in FIG. 1b;

[0043]FIGS. 2a,b,c,d show alternative embodiments of the invention inschematic cross-section views;

[0044]FIGS. 3a,b,c show schematic cross-section views of the stages ofmanipulation of an edge insulation piece according to the invention;

[0045]FIG. 4 shows a schematic perspective view of a corner portion of afurther embodiment of an edge insulation piece; and

[0046]FIG. 5 shows a schematic plan view of the corner portion of FIG. 4before the material is folded.

[0047] As shown in the Figures, an edge insulation piece 1 according tothe invention comprises a thin sheet of material 2 which is manipulatedby bending, rolling or other forming. In one embodiment, a thin layer ofinsulation material 3 is interleaved between the two layers of the thinsheet of material 2, which are folded around the insulation layer 3during forming of the edge piece 1. A further layer of insulationmaterial 4 may be rolled within the edge piece 1 as it is formed (asshown in FIGS. 3a,b and c). This interleaving of thin layers ofinsulation material 3,4 prevents the surfaces of the thin sheet ofmaterial 2 from touching each other and also helps to insulate thematerial 2 from the top and bottom panels 5,6 of a vacuum insulationpanel 7 when the edge piece 1 is inserted around the edge of the panel7. The edge piece 1 may contact the internal insulation material 8 inthe interior 9 of the panel 7. In the embodiments illustrated, theinterior 9 of the panel 7 is held under a vacuum and thus the layer ofinsulation material 3 is also subject to the vacuum, with the otherlayer 4 being open to the atmosphere 10. The layer 4 is also subject tosignificant compression due to the folding processes employed in formingthe edge insulation piece 1.

[0048] The edge piece 1 is attached to the top and bottom panels 5,6 bysuitable means such as welding or adhesive means. The panel 5 has a hotface H and the panel 6 has a cold face C and the edge insulation piece 1serves to reduce the transference of heat across the edge region of thewhole panel 7. The edge piece 1 may be formed as a continuous edging forarrangement around the edges of the panel 7 such that when the edgeinsulation piece 1 is positioned around the circumference of the panel7, the end faces of the edging piece 1 will meet together and can bewelded or joined together to make a complete seal around the peripheryof the panel 7.

[0049] As shown in FIGS. 1a and 1 b, the ends 11,12 of the edge piece 1,which are extensions of the sheet 2, may be attached to the end faces ofthe panels 5,6. Alternative arrangements are shown in FIGS. 1c,d,e,f andg. In these embodiments, the panels 5 and 6 are formed from thin sheetsand the ends 5 a,6 a of the panels 5,6 are folded perpendicularly to theface of the panels 5,6 to form flanges. The ends 11,12 of the edge piece1 may be attached to these flanges 5 a,6 a.

[0050] As shown in FIGS. 1d,e,f and g, the ends of the end pieces 11,12may be capped by inverted ‘V’ shapes or ‘top hat’ shapes 11 a,12 a toimprove the seal. These may be formed as extensions of the end pieces11,12 (FIG. 1d), as extensions of the flanges 5 a,6 a (FIG. 1e) or asseparate pieces 11 b,12 b (FIGS. 1f and 1 g).

[0051] The end pieces 11,12 and flanges 5 a,6 a may also be folded flatagainst the other faces of the panels 5,6 or sheet 2 to reduce the riskof damage to the edge sealing around the panel 7, provided that thisdoes not compromise the insulation.

[0052] The edge piece 1 may be further coated over part or all of itslength with a low emissivity material 13 to minimise radiative losses.This layer 13 is preferably formed on the face of the sheet 2 that isdirected towards the atmosphere 10, so that radiation losses to theatmosphere are reduced. Alternatively or additionally this furthercoating 13 may comprise a gas impermeable layer to form a gasimpermeable barrier.

[0053] Some of the possible alternative configurations of the edge piece1 are shown schematically in FIGS. 2a,b,c,d.

[0054]FIGS. 2a and b show embodiments with layers 3,4 of insulationbetween the layers of the sheet of material 2 whereas FIGS. 2c and dshow embodiments without the layers of insulation. It will beappreciated by those skilled in the art that all the embodiments of theinvention can be made with or without the layers of insulation betweenthe layers of the sheet of material 2.

[0055] By taking very thin material 2, bending and or rolling this, itis possible to form a small compact edge 1 with significantly reducedlosses as compared to conventional edging techniques. This can beimproved further by the addition of a thin insulation material 3,4interleaved with the thin material 2, not only does this prevent thesurfaces from touching but the compression of the insulating materialtends to improve its insulating properties. This edging material 1 canthen be bonded to the top and bottom skins 5,6 by various means mostsuited to their environment; stainless steel is typically welded. Theprovision of end portions 11,12 in the shape of inverted ‘top hats’ orinverted ‘V’s 11 a,12 a can improve the seal. The edging material 1 canbe produced in any length and joined at each end by a small lengthhaving no insulation, fusing of all layers together and forming anair-tight seal.

[0056] A typical problem of using any type of edge assembly is thesealing of the corners and this can be accommodated using the sametechniques of bending and folding. A typical example is shown in FIG. 4depicting a radiused rolled corner 40. FIG. 5 indicates what theoriginal source material 50 would look like before folding. The material50 has two extending portions 51,52 corresponding to the corner position(40 of FIG. 4). These portions 51,52 are folded and rolled as the edgepiece 1 is assembled to form a radiused corner shape. Most corner shapescan be accommodated using these folding techniques. It is feasible thatthese folding techniques may have applications in other technologies.

[0057] The edge 1 can be made out of any thin material suitable for thetemperatures and environment encountered. Any insulation 3,4 interleavedwith the thin material can be applied by way of a coating prior tomanipulation or forming and because the edge material 1 is made out ofone continuous piece it means it can be completely sealed, enablingvacuums to be formed and kept should they be required. This process canalso be performed in reverse where the thin material 2 can be depositedonto the insulation 3,4 or any combination of this. Where hightemperature differences are to be maintained then part or all of theedge material 1 can be coated with a low emissivity material 13 tominimise radiative losses.

[0058] Tests have been conducted using 50-micron (0.002 inch) stainlesssteel with excellent results indicating insulation properties twice asgood as existing designs. For a roll of approximately 10 mm×7 mm of 50micron stainless steel with 0.5 mm ceramic paper insulation, typicallosses have been found to be less than 1.4 watts/m length of edge at200° C. temperature difference.

[0059] In a further test, a prototype panel was made incorporating anedge piece in accordance with the invention and tested for thermallosses. The panel was 270 mm×270 mm×9.7 mm, with ceramic fibre andaluminium foil as filler. The structure of the edge piece enabled thepanel to be extremely light, with the top and bottom skins of the panelbeing 0.1 mm thick and the density of the panel being only 0.55 gms/cm³.The edge piece was formed using 0.075 mm stainless steel sheet formed asa roll and incorporated around the panel. The panel was evacuated to amodest vacuum of no better than 0.1 mBar. When tested with a hot facetemperature of 322° C. and a cold face temperature of 51° C., with anambient temperature of 35° C., the panel demonstrated a thermalconductivity value of about 3.3 mW/mK.

[0060] It is believed that significant improvements can be made on theseinitial results.

[0061] An edge insulation piece in accordance with the invention has theadvantage that it enables the conductive path between the faces of aninsulation panel to be increased without increasing the distance betweenthe panels. The invention has the additional advantage that it alsoenables the edge insulation piece on an insulation panel to allow forthermal expansion movements of the panel to be accommodated within thestructure of the edge insulation piece itself.

[0062] Although the improvements are aimed primarily at Vacuum SuperInsulation panels the invention can be applied to all other applicationswhere a temperature difference is to be maintained or otherwisecontrolled and it can be applied to all shapes and sizes.

1. An edge insulation piece for an insulation article characterised inthat the edge insulation piece comprises a thin sheet of material, thethin sheet of material having been manipulated to a shape having a longconductive path within a small cross-sectional area.
 2. An edgeinsulation piece according to claim 1 characterised in that the thinsheet of material is manipulated by bending, shaping or otherwisedeforming the thin sheet of material or by extruding, moulding orcasting.
 3. An edge insulation piece according to claim 1 or claim 2characterised in that part or all of the surfaces of the thin sheet ofmaterial are coated with a low emissivity material.
 4. An edgeinsulation piece according to any one of the preceding claimscharacterised in that part or all of the surfaces of the thin sheet ofmaterial are coated with a gas-impermeable layer.
 5. An edge insulationpiece according to any one of the preceding claims characterised in thatit further comprises a thin layer of insulation material sandwichedbetween layers of the thin sheet of material to improve the insulationbetween each layer and to prevent contact of any part of the thin sheetof material with adjacent layers.
 6. An edge insulation piece accordingto claim 5 characterised in that the insulation layer comprises a thincoating deposited, coated or otherwise joined to the thin sheet ofmaterial prior to manipulation of the thin sheet of material or aftermanipulation of the thin sheet of material.
 7. An edge insulation pieceaccording to claim 5 or claim 6 characterised in that the insulation isvariable in thickness depending upon its relationship to the hot andcold surfaces of the insulation article.
 8. An edge insulation pieceaccording to any one of the preceding claims characterised in that theedge insulation piece is formed by folding or rolling the thin sheet ofmaterial.
 9. An edge insulation piece according to claim 8 characterisedin that the thin sheet is folded to form two adjacent layers connectedat the fold end.
 10. An edge insulation piece according to claim 9characterised in that the folded sheet is folded or rolled to form theedge insulation piece.
 11. An edge insulation piece according to claim 9or claim 10 characterised in that the edge insulation piece furthercomprises a layer of insulation material sandwiched between the twolayers of the folded sheet.
 12. An edge insulation piece according toclaim 11 characterised in that the edge insulation piece furthercomprises a further layer of insulation material positioned adjacent toone of the layers of the folded sheet and folded or rolled within thelayers of the folded or rolled edge insulation piece.
 13. An edgeinsulation piece according to any one of the preceding claimscharacterised in that the edge insulation piece has means to join it toseparated parts of an article.
 14. An edge insulation piece according toclaim 13 characterised in that the means to join the edge insulationpiece to an article comprise extending end portions that can be attachedto the respective separated parts of such an article by welding,adhesive means or other suitable means.
 15. An edge insulation pieceaccording to claim 14 characterised in that the extending end portionsare covered with an inverted ‘V’ or ‘top hat’ shaped sealing means. 16.An edge insulation piece according to any one of the preceding claimscharacterised in that the edge insulation piece comprises a cornerportion, the edge insulation piece comprising a thin sheet of materialwith extending portions corresponding to the corner portion.
 17. An edgeinsulation piece according to claim 16 characterised in that theextending portions are triangular in shape.
 18. An edge insulation pieceaccording to claim 16 or claim 17 characterised in that the manipulatedcorner portion comprises a radiused rolled corner.
 19. A corner portionfor an edge insulation piece comprising a thin sheet of material withextending portions corresponding to the corner portion and the thinsheet of material having been manipulated to effect a long conductivepath within a small cross-sectional area.
 20. A corner portion accordingto claim 19 characterised in that the extending portions are triangularin shape.
 21. A corner portion according to claim 19 or claim 20characterised in that the manipulated corner portion comprises aradiused rolled corner.
 22. A vacuum insulation panel comprising an edgeinsulation piece in accordance with any one of the preceding claims. 23.A method of manufacturing an edge insulation piece for an insulationarticle comprising the steps of: folding a thin sheet of material toform two layers; and manipulating the thin sheet of material to effect along conductive path within a small cross-sectional area.
 24. A methodof manufacturing an edge insulation piece according to claim 23characterised in that the step of manipulating the thin sheet ofmaterial comprises bending, shaping or otherwise deforming the thinsheet of material or extruding, moulding or casting.
 25. A method ofmanufacturing an edge insulation piece according to claim 23 or 24characterised in that the method includes the further step of coatingpart or all of the surfaces of the thin sheet of material with a lowemissivity material.
 26. A method of manufacturing an edge insulationpiece according to any one of claims 23 to 25 characterised in that themethod includes the further step of coating part or all of the surfacesof the thin sheet of material with a thin layer of gas impermeablematerial to provide an impermeable gas barrier.
 27. A method ofmanufacturing an edge insulation piece according to any one of claims 23to 26 characterised in that the method includes the further step ofsandwiching a thin layer of insulation material between layers of thethin sheet of material to improve the insulation between each layer andto prevent contact of any part of the thin sheet of material withadjacent layers.
 28. A method of manufacturing an edge insulation pieceaccording to any one of claims 23 to 27 characterised in that the methodincludes the further step of sandwiching a thin layer of gas impermeablematerial between layers of the thin sheet of material to provide animpermeable gas barrier.
 29. A method of manufacturing an edgeinsulation piece according to claim 28 characterised in that theinsulation is formed by depositing, coating or otherwise joining a thincoating to the thin sheet of material prior to manipulation of the thinsheet of material or after manipulation of the thin sheet of material.30. A method of manufacturing an edge insulation piece according to anyone of claims 23 to 29 characterised in that the edge insulation pieceis formed by folding or rolling the thin sheet of material.
 31. A methodof manufacturing an edge insulation piece according to claim 30characterised in that the thin sheet is folded to form two adjacentlayers, connected at the fold end.
 32. A method of manufacturing an edgeinsulation piece according to claim 31 characterised in that the foldedsheet is folded or rolled to form the edge insulation piece.
 33. Amethod of manufacturing an edge insulation piece according to claim 32or claim 32 characterised in that a layer of insulation material issandwiched between the two layers of the folded sheet.
 34. A method ofmanufacturing an edge insulation piece according to claim 33characterised in that a further layer of insulation material ispositioned adjacent to one of the layers of the folded sheet and isfolded or rolled within the layers of the folded or rolled edgeinsulation piece.
 35. A method of manufacturing an edge insulation pieceaccording to any one of claims 23 to 34 characterised in that the methodincludes the further step of squashing the shaped edge insulation pieceto limit its overall size.
 36. A method of manufacturing an edgeinsulation piece according to any one of claims 23 to 35 characterisedin that the manipulation of the thin sheet of material is carried out bya series of rollers and/or guides positioned in relation to each otherto effect gradual changes without significant deformation of thematerial.
 37. A method of manufacturing an edge insulation pieceaccording to any one of claims 23 to 36 characterised in that themanipulation of the thin sheet of material is carried out by a twistingprocess to effect gradual changes without significant deformation of thematerial.
 38. A method of manufacturing an edge insulation pieceaccording to any one of claims 23 to 37, the edge insulation piececomprising a corner portion for an insulation article, comprising thefurther step of: providing a thin sheet of material with extendingportions corresponding to the corner portion.